Railroad cars generally use DC power or AC power supplied from overhead electric lines to obtain electric power for driving their motors. The electric power is generated by a power conversion device installed in the railroad cars as well.
The DC power or the AC power supplied from the overhead electric lines is received by a pantograph, and then supplied to the motor via various electric circuits such as a transformer and the power conversion device. The electric circuits have sensors such as a voltage detector and a current detector, which, for example, are used to monitor whether any malfunction such as a short-circuit occurs in the electric circuits. The sensors are also used by the power conversion device to generate the electric power for driving the motor.
Patent Document 1:JP-A-2010-273455